Plant protective microemulsion composition comprising pyrethroids

ABSTRACT

A solution of a plant protective agent is disclosed, which comprises per liter of solution 
     1 to 150 g/l of one or more synthetic pyrethroid(s) as active ingredient(s) and 
     40 to 70 g/l of ethoxylated (EO=10 to 14)-propoxylated (PO)=18 to 22) nonylphenol, 
     10 to 20 g/l of linear calcium dodecylbenzenesulfonate, 
     90 to 120 g/l of polyoxyethylene(20)-sorbitan monolaurate as the surface active agents, 
     and a solvent mixture (A) consisting of 
     9 to 11% by volume of hydrogenated aliphatic hydrocarbon containing 45% of naphthene, 18 to 30% by volume of propylene glycol, 28 to 35% by volume of pine fatty acid, 23 to 30% by volume of sunflower oil, 5 to 10% by volume of an 1:1 by volume mixture of methanol or ethanol with isobutanol in an amount to complete the volume to 1 liter.

FIELD OF THE INVENTION

This invention relates to novel plant protective microemulsion compositions, more particularly to solutions containing pyrethroids as active ingredients as well as to stable aqueous microemulsions prepared therefrom. The invention further relates to the preparation and use of these solutions and microemulsions.

BACKGROUND OF THE INVENTION

The aqueous microemulsions according to the invention can be transformed to other compositions such as aerosols by using suitable auxiliary materials.

It is known that synthetic pyrethroids are used to a continuously increasing extent in the state of the art plant protection since a satisfactory protection can be achieved by applying the active ingredient in amounts as low as 10 to 100 g/ha and on the other hand, the residue of the active ingredient becomes negligible within a relatively short time of decomposition. The pyrethroid-type active ingredients are used in the form of wettable powders (WP), suspension concentrates (FW) and most frequently as microemulsion compositions (EC). General demands made on the state of the art emulsion concentrates comprise

a) ensuring the very dilute emulsion phase state in the concentration for application by an economical amount [75 to 150 g/liter (abbreviated: g/l] of a surface active agent; and

b) avoiding the use of xylene as solvent because of problems connected with safety, environmental protection and phytotoxicity.

The low amount of the surface active agent can be ensured by a suitable selection of state of the art surface active substances. For replacing xylene, the solvent manufacturers developed specific but expensive novel types of solvents whereas the formulating manufacturers made efforts to replace the solvents by aqueous systems. Thus, in the German patent specification NO. 3,235,612, aqueous microemulsions are described which contain: 0.1 to 80% by weight of active ingredient together with 1 to 20% by weight of a particular emulsifier mixture and optionally 1 to 30% by weight of organic solvent, being partly miscible with water; as well as water. The particular emulsifier is a mixture of an alkylaryl polyglycol ether with an alkylarylsulfonate salt. The emulsion stability of the emulsion concentrates reported in the German patent specification No. 3,508,643 is ensured by polyvinyl alcohol and an organic acid. The aqueous microemulsions described in the German patent specification No. 3,624,910 contain as emulsifiers a phenol or a phenolate salt substituted by ethoxylated and phosphorylated styryl group in combination with one or more non-phosphorylated emulsifying agent(s) together with 5 to 30% by weight of an usual solvent.

The aqueous microemulsions set forth in the published European patent application No. 0,160,182 contain pyrethroids and phosphoric acid esters as active ingredients and ethoxylated tristyrylphenol, ethoxylated distyrylphenol-ammonium sulfate and an alkylarylsulfonate as emulsifying agents. Emulsion concentrates containing low molecular aliphatic alcohols and ketones as stabilizing agents are described in the published Japanese patent application No. 51-59778.

Another problem of the EC-type compositions arises in that a stable spray liquid, required to remain stable in most cases for at least 24 hours, has to be prepared from the given emulsion concentrates by using waters with various hardnesses. In addition, synthetic pyrethroids are weakly soluble in aliphatic hydrocarbons and apolar solvents which in turn are preferred from the viewpoint of phytotoxicity, environmental protection and safety; thus, they can meet the criterion of the cold-resistance only with difficulties.

OBJECT OF THE INVENTION

The object of the invention is to prepare an emulsion solution (pre-formulation) with a composition meeting the demands made on the state of the art emulsion concentrates such as the low surface active agent content, absence of aromatic solvents and the possibility of preparing a stable aqueous microemulsion even under the extreme use conditions.

SUMMARY OF THE INVENTION

Thus, the present invention relates to a novel solution of a plant protective agent, 1 liter of which contains

1 to 150 g/l of one or more synthetic pyrethroid(s) as active ingredient(s) and

40 to 70 g/l of ethoxylated (EO=10 to 14)-propoxylated (PO=18 to 22) nonylphenol,

10 to 20 g/l of linear calcium dodecylbenzenesulfonate,

90 to 120 g/l of polyoxyethylene(20)-sorbitan monolaurate as surface active agents,

and a solvent mixture (A) consisting of

9 to 11% by volume of hydrogenated aliphatic hydrocarbon containing 45% of naphthene,

18 to 30% by volume of propylene glycol,

28 to 35% by volume of pine fatty acid,

23 to 30% by volume of sunflower oil,

5 to 10% by volume of an 1:1 by volume mixture of methanol or ethanol, respectively with isobutanol in an amount supplementing up to 1 liter.

One liter of the solution of the plant protective agent according to the invention can be prepared by dissolving

1 to 150 g/l of synthetic pyrethroid,

40 to 70 g/l of ethoxylated (EO=10 to 14)-propoxylated (PO=18 to 22) nonylphenol,

10 to 20 g/l of linear calcium dodecylbenzenesulfonate,

90 to 120 g/l of polyoxyethylene(20)-sorbitan monolaurate

in 500 ml of a solvent mixture (A) consisting of

9 to 11% by volume of a hydrogenated aliphatic hydrocarbon containing 45% of naphthene,

18 to 30% by volume of propylene glycol,

28 to 35% by volume of pine fatty acid,

23 to 30% by volume of sunflower oil,

5 to 10% by volume of an 1:1 by volume mixture of methanol or ethanol, transmission with isobutanol and supplementing the solution thus obtained up to 1 liter with the solvent mixture (A).

The invention further relates to a transparent emulsion of a plant protective agent having

an average drop size below 100 μm;

a relative interfacial tension below 3 mN/m; and

a light transmission

above 95% in 0.01% concentration,

above 90% in 0.1% concentration and

above 85% in 1% concentration

through a layer thickness of 10 mm after an examination period of 120 minutes,

which comprises 0.01 to 1.0% by volume of the above solution and water of a hardness of 0 to 500 ppm in an amount necessary to fill up to 100% by volume.

As synthetic pyrethroids, the tetramethrin [chemically 3,4,5,6-tetrahydrophthalimidomethyl (1RS)-cis-trans-chrysanthemate] and/or deltamethrin [chemically (S)-α-cyano-3-phenoxybenzyl (1R)-cis-3-(2,2-dibromvinyl)-2,2-dimethylcyclopropanecarboxylate] and/or fenpropathrin [chemically (RS)-α-cyano-3-phenoxybenzyl 2,2,3,3-tetramethylcyclopropane carboxylate] and/or fenvalerate [chemically (RS)-α-cyano-3-phenoxybenzyl (RS)-2-(4-chlorophenyl)-3-methylbutylate] and/or flucitrinate ]chemically (RS)-α-cyano-3-phenoxybenzyl (RS)-2-(4-difluoromethoxyphenyl)-3-methylbutyrate] and/or permethrin [chemically 3-phenoxybenzyl 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylate] and/or cypermethrin [chemically (RS)-α-cyano-3-phenoxybenzyl (1RS)-cis-trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylate] and/or the enantiomeric pairs of (RS)-α-cyano-3-phenoxybenzyl (1RS)-cis-trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylate (1R)-cis-(S)+(1S)-cis-(R) and (1R)-trans-(S)+(1S)-trans-(R) or the mixtures thereof may be contained in the plant protective compositions according to the invention.

The stability of the diluted compositions according to the invention was studied between the concentration limits of 0.01 to 1% in the presence of salts resulting in a water hardness of 34.2 to 342 ppm by using the standardized COPAC method. Samples were taken from the emulsions after 0, 30 and 120 minutes, then after 24 hours and the drop size distribution (Zetasizer IIc) in the samples and their light transmittance at 845 μm wavelength in a 10 mm glass cuvet was examined.

The interfacial tension of the composition as related to water (CIPAC A and D) was determined by using the hanging drop method.

The composition, physico-chemical characteristics and effects of the compositions according to the invention are illustrated in detail by the following non-limiting Examples.

EXAMPLE 1

The preparations according to the compositions 1 to 16 were prepared uniformly by using the following method.

1000 ml of the solution were weighed together from the solvent mixture according to the volume ratio. 500 ml of the solution obtained were weighed into a graduated cylinder of 1000 ml volume and the synthetic pyrethroids and emulsifiers were dissolved therein. After complete dissolution, the solution was filled up to 1000 ml with the above solvent. The compositions of the preparations according to the Examples are summarized in Tables 1 and 2. The characteristics of the compositions are shown in Table 3.

The following abbreviations are used in the Tables:

    ______________________________________                                                                  Abbreviation in                                       Components               the Tables                                            ______________________________________                                         Ethoxylated(EO = 13)-propoxylated(PO = 21)                                                              EPN                                                   nonylphenol                                                                    Linear calcium dodecylbenzenesulfonate                                                                  LDBC                                                  Polyethoxylene(20)-sorbitan monooleate                                                                  PSMO                                                  Propylene glycol         PGL                                                   Pine fatty acid          PFA                                                   Sunflower oil            SO                                                    1:1 by volume mixture of methanol or                                                                    MB or EB,                                             ethanol, respectively, with isobutanol                                                                  respectively                                          Hydrogenated aliphatic hydrocarbon                                                                      HAM                                                   mixture containing 45% of naphthene                                            ______________________________________                                    

                                      TABLE 1                                      __________________________________________________________________________     Compositions                                                                   Components        1   2   3   4   5   6   7   8                                __________________________________________________________________________     Cypermethrin (g/l)                                                                               150 75  --  --  --  --  --  --                               (1R)-cis-(S) + (1S)-cis-(R) (g/l)                                                                --  --  50  --  40  30  20  30                               (1R)-trans-(S) + (1S)-trans-(R) (g/l)                                                            --  --  --  50  60  70  30  20                               EPN (g/l)         70  40  60  60  60  65  60  60                               LDBC (g/l)        20  10  14  15  14  18  14  14                               PSMO (g/l)        120 90  105 105 105 115 105 105                              completed to 1000 ml with:                                                     PGL (% by vol.)   28.6                                                                               19.1                                                                               19.1                                                                               19.1                                                                               23.8                                                                               23.8                                                                               23.8                                                                               23.8                             PFA (% by vol.)   28.6                                                                               33.3                                                                               33.3                                                                               33.3                                                                               31.0                                                                               28.6                                                                               31.0                                                                               31.0                             SO (% by vol.)    23.8                                                                               28.6                                                                               28.6                                                                               23.8                                                                               26.2                                                                               28.6                                                                               26.2                                                                               26.2                             EB (% by vol.)     9.5                                                                                9.6                                                                                9.5                                                                                9.5                                                                                9.5                                                                                9.5                                                                                9.5                                                                                9.5                             HAM (% by vol.)    9.5                                                                                9.5                                                                                9.5                                                                                9.5                                                                                9.5                                                                                9.5                                                                                9.5                                                                                9.5                             __________________________________________________________________________

                  TABLE 2                                                          ______________________________________                                          Compositions                                                                  ______________________________________                                         Components   9       10      11    12    13                                    ______________________________________                                         Deltamethrin (g/l)                                                                          25      --      --    --    --                                    Fenpropathrin (g/l)                                                                         --      100     --    --    --                                    Fenvalerate (g/l)                                                                           --      --      110   --    --                                    Permethrin (g/l)                                                                            --      --      --    --    250                                   EPN (g/l)    60      60      60    60    70                                    LDBC (g/l)   14      14      18    14    20                                    PSMO (g/l)   105     105     115   105   12                                    supplemented to                                                                1000 ml with:                                                                  PGL (% by vol.)                                                                             19.1    23.8    23.8  19.1  23.8                                  PFA (% by vol.)                                                                             28.6    28.6    31.0  33.3  31.0                                  SO (% by vol.)                                                                              28.6    28.6    26.2  23.8  26.2                                  MB (% by vol.)                                                                               9.5    --      --    --     9.5                                  EB (% by vol.)                                                                              --       9.5     9.5   9.5  --                                    HAM (% by vol.)                                                                              9.5     9.5     9.5   9.5   9.5                                  ______________________________________                                         Components        14       15       16                                         ______________________________________                                         (1R)-trans-(S) + (1S)-trans-(R)                                                                  50       50       50                                         Tetramethrin       5        5        5                                         Piperonylbutoxide 100      --       50                                         EPN (g/l)         65       40       60                                         LDBC (g/l)        18       10       14                                         PSMO (g/l)        115      90       105                                        supplemented to 1000 ml with:                                                  PGL (% by vol.)     23.8     19.1     28.6                                     TLS (% by vol.)     31.0     33.3     28.6                                     SO (% by vol.)      26.2     28.6     23.8                                     EB (% by vol.)      9.5      9.5      9.5                                      HAM (% by vol.)     9.5      9.5      9.5                                      ______________________________________                                    

                                      TABLE 3                                      __________________________________________________________________________      Physico-chemical characteristics                                              __________________________________________________________________________     Example No.                                                                               1            2            3            4                            __________________________________________________________________________     Dilution (%)                                                                                 0.01                                                                               0.1                                                                                1.0                                                                                 0.01                                                                               0.1                                                                                1.0                                                                                 0.01                                                                               0.1                                                                                1.0                                                                                 0.01                                                                               0.1                                                                                1.0               light transmission %                                                             0 h       98  94  90   99  95  87  95   92  85   97  93  82                  0.5 h      100  97  92  100  96  88  97   33  85   99  94  82                    2 h      100  98  92  100  96  88  97   94  87  100  94  84                   24 h      100  97  90  100  96  89  96   94  87  100  94  84                  Surface tension  2            0            0            3                      (mN/m)                                                                         Average drop size                                                                              83           57           64           87                      (nm)                                                                           __________________________________________________________________________     Example No.                                                                               5            6            7            8                            __________________________________________________________________________     Dilution (%)                                                                                 0.01                                                                                0.1                                                                               1.0                                                                                 0.01                                                                               0.1                                                                                1.0                                                                                 0.01                                                                               0.1                                                                                1.0                                                                                 0.01                                                                               0.1                                                                                1.0               light transmission %                                                             0 h      95   95  87   99  95  80   97  95  82  97   92  85                  0.5 h      97   94  89  100  97  82   98  97  83  98   93  86                    2 h      97   95  89  100  97  85  100  97  85  98   94  86                   24 h      96   94  87  100  97  85  100  97  83  98   94  86                  Surface tension  2            0            1            1                      (mN/m)                                                                         Average drop size                                                                              91           78           66           69                      (nm)                                                                           __________________________________________________________________________     Example No.                                                                               9            10           11           12                           __________________________________________________________________________     Dilution (%)                                                                                 0.01                                                                               0.1                                                                                1.0                                                                                 0.01                                                                               0.1                                                                                1.0                                                                                 0.01                                                                               0.1                                                                                1.0                                                                                 0.01                                                                               0.1                                                                                1.0               light transmission %                                                             0 h      95   94  85   98  95  80  100  95  85   99  96  87                  0.5 h      98   94  86   98  96  85  100  96  86  100  96  86                    2 h      98   95  86  100  96  85  100  96  86  100  97  88                   24 h      98   95  85  100  96  85  100  95  87  100  97  88                  Surface tension  0            1            1            0                      (mN/m)                                                                         Average drop size                                                                              93           98           76           84                      (nm)                                                                           __________________________________________________________________________     Example No. 13          14           15           16                           __________________________________________________________________________     Dilution (%)                                                                                0.01                                                                                0.1                                                                                1.0                                                                                 0.01                                                                               0.1                                                                                1.0                                                                                0.01                                                                                0.1                                                                                1.0                                                                                 0.01                                                                               0.1                                                                                1.0               light transmission %                                                             0 h      95   93  86  100  97  80  100  100 86  100  96  87                  0.5 h      97   94  87  100  97  84  99   96  87  100  94  84                    2 h      97   94  87   98  95  85  99   96  86   95  94  84                   24 h      97   94  87   97  95  85  99   97  88   94  92  85                  Surface tension  1            2            0            1                      (mN/m)                                                                         Average drop size                                                                              72           86           64           68                      (nm)                                                                           __________________________________________________________________________

EXAMPLE 17

Emulsions with a 1000-fold dilution were prepared from the samples according to the above formulation Examples by using CIPAC D water, then the activity of the emulsions was determined in a fresh state and after standing for 5 hours.

The samples taken from the upper third of the emulsions were further diluted with CIPAC D water in the given moments to obtain emulsions with concentrations of 2.5, 1.25, 0.625, 0.3125, 0.15625 and 0.078125 ppm, calculated on the active ingredient. Two ml of these emulsions were sprayed into Petri plates of 9 cm diameter by using a Potter's tower.

After complete drying, twenty 3-day old female houseflies (Musca domestica WHO/SRS with a body weight of 21±1.5 mg each) mildly narcotized by carbon dioxide were put into the Petri dishes and after 24 hours the number of the dead flies was determined. This examination was carried out for each concentration in 3 parallels.

From the data obtained the equipotential concentrations (LC₅₀ values) expressing the activity were calculated by probit analysis. The lower LC₅₀ values mean higher activities. The results are summarized in Table 4.

                  TABLE 4                                                          ______________________________________                                                       Duration of the                                                                activity examina-                                                              tion after prep-                                                               aration of the                                                   Samples       emulsion (hour)                                                                             LC.sub.50 ±                                                                         s    b                                      ______________________________________                                         CNX 5 EC Example,                                                                            0            0.564   0.047                                                                               2.26                                   control                                                                        CHX 5 ME Example 7,                                                                          0            0.263   0.021                                                                               2.43                                   product                                                                        CHX 5 EC Example,                                                                            5            0.594   0.052                                                                               2.131                                  control                                                                        ______________________________________                                         Composition of CHX 5 EC:                                                       (1R)-cis-(S) + (1S)-cis-(R) (g/l)                                                                      20                                                     (1R)-trans-(S) + (1S)-trans-(R) (g/l)                                                                  30                                                     Emulsifiers (g/l)       100                                                    Xylene completed to     1000   ml                                              ______________________________________                                    

EXAMPLES 18 to 27

The aerosols shown in Table 5 are prepared from the aqueous microemulsions according to the invention in a manner known per se.

                  TABLE 5                                                          ______________________________________                                                    Example No.                                                                    18  19    20    21  22  23  24  25  26  27                          ______________________________________                                         Composition of Exam-                                                                        40    40    --  --  --  --  --  --  --  --                        ple 4 in an aqueous                                                            dilution of 1%                                                                 (% by vol.)                                                                    Composition of Exam-                                                                        --    --    40  40  --  --  --  --  --  --                        ple 7 in an aqueous                                                            dilution of 1%                                                                 (% by vol.)                                                                    Composition of Exam-                                                                        --    --    --  --  40  40  --  --  --  --                        ple 14 in an aquoue                                                            dilution of 1%                                                                 (% by vol.)                                                                    Composition of Exam-                                                                        --    --    --  --  --  --  40  40  --  --                        ple 15 in an aqueous                                                           dilution of 1%                                                                 (% by vol.)                                                                    Composition of Exam-                                                                        --    --    --  --  --  --  --  --  40  40                        ple 16 in an aqueous                                                           dilution of 1%                                                                 (% by vol.)                                                                    Ethanol (% by vol.)                                                                         20    --    20  --  20  --  20  --  20  --                        Liquid propane-butane                                                                       40    40    40  40  40  40  40  40  40  40                        (% by vol.)                                                                    Isopropanol  --    20    --  20  --  20  --  20  --  20                        (% by vol.)                                                                    ______________________________________                                     

What is claimed is:
 1. A solution of a plant protective agent which comprisesas active ingredient 1-150 g of at least one synthetic pyrethroid as a surface active agent 40-70 g of ethoxylated (EO=10-14)-propoxylated (PO=18-22) nonylphenol, 10-20 g of linear calcium dodecylbenzene sulfonate, and 90-120 g of polyoxyethylene (20)-sorbitan monolaurate, and a solvent mixture in a quantity needed for 1 liter from the following (A) composition: 9-11% by volume of a hydrogenated aliphatic hydrocarbon containing 45% of naphthene, 18-30% by volume of propylene glycol, 28-35% by volume of pine fatty acid, 25-30% by volume of sunflower oil, and 5-10% by volume of a 1:1 by volume mixture of methanol or ethanol with isobutanol.
 2. Process for the preparation of a plant protective agent solution according to claim 1, which comprises dissolving1-150 g of a synthetic pyrethroid, 40-70 g of ethoxylated (EO=10-14)-propoxylated (PO=18-22) nonylphenol, 10-20 g of linear calcium dodecylbenzene sulfonate, 9- 120g of polyoxyethylene (20)-sorbitan monolaurate in 500 ml of a solvent mixture of the following composition (A): 9-11% by volume of a hydrogenated aliphatic hydrocarbon containing 45% of naphthene, 18-35% by volume of propylene glycol, 28-35% by volume of pine fatty acid, 28-30% by volume of sunflower oil, 5-10% by volume of an 1:1 by volume mixture of methanol or ethanol and isobutanol,and the solution thus obtained is completed to 1 liter by the solution mixture (A).
 3. Transparent plant protective agent emulsion having an average drop size below 100 μm;a relative interfacial tension below 3 mH/m, and a light transmission capacity at a layer thickness of 10 mm after an examination period of 120 minutes in a concentration after an examination period of 120 minutes in a concentration of 0.01% T above 95% 0.1% T above 90% and 1% T above 80%,which contains 0.01 to 1.0% by volume of the solution according to claim 1 and water of a hardness of 0-500 ppm of the sum of all milliequivalents of cations contributing to hardness, calculated as CaCo₃.
 4. Plant protective compositions according to claim 1, which comprise synthetic pyrethroids 3,4,5,6-tetrahydro-phthalimidomethyl (1RS)-cis-trans-chrysanthemate;(S)-α-cyano-3-phenoxybenzyl (1R)-cis-3-(2,2-dibromovinyl)-2,2-dimethyl-cyclopropane carboxylate; (RS)-α-cyano-3-phenoxybenzyl-(RS)-2-(4-chlorophenyl)-3-methylbutyrate 3-phenoxybenzyl-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylate; (RS)-α-cyano-3-phenoxybenzyl-(1RS)-cis-trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylate; or the enantiomeric pairs of (RS)-α-cyano-3-phenoxybenzyl (1RS)-cis-trans-3-3(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylate (1R)-cis-(S)÷(1S)-cis-(R) and (1R)-trans-(S)÷(1S)-trans-(R); or mixtures thereof.
 5. A solution of a plant protective agent which comprises,(a) as active ingredients:(1) 20 g of the cypermethrin isomer pair 1RcisS and 1ScisR; and (2) 30 g of the cypermethrin isomer pair 1RtransS and 1StransR; (b) as a surface active agent:(1) 60 g of ethoxylated(EO=13)-propoxylated(PO=21) nonylphenol; (2) 14 g of linear calcium dodecyl benzene sulfonate; and (3) 105 g of polyoxyethylene(20)-sorbitan monooleate; and (c) as a solvent mixture in a quantity needed for 1 liter from the following composition:(1) 23.8% by volume of propylene glycol; (2) 31.0% by volume of pine fatty acid; (3) 26.2% by volume of sunflower oil; (4) 9.5% by volume of a 1:1 parts by volume mixture of ethanol and isobutanol; and (5) 9.5% by volume of a hydrogenated aliphatic hydrocarbon mixture comprising 45% of naphthene. 